My tl;dr on last night's loooong Neuralink presentation.
Predicted six months before they hope to get FDA approval for human clinical trials.
Initial application will allow completely paralyzed individuals to communicate with thought. They have crude versions of this working now in monkeys, so this should be relatively easy to do in humans. They talked about two other applications, both of which will require a lot more research work.
One new one is vision restoration. They have already demonstrated being able to create bright flashes in a monkey's visual field of view in precise locations. From there to creating a real time crude grayscale representation of what a camera sees is a relatively small step from a theoretical perspective.
They showed how they can contract and elongate a pig's leg muscles through motor cortex stimulation. However fixing a spinal cord injury to allow movement has a fairly long way to go and will require new research and technologies. Doable, but longer term (for instance, now you are integrating into the spinal cord rather than the brain, and they just haven't started doing that yet).
Like all of Elon's companies, they are hardware rich during this R&D phase and have continually iterated every aspect of their technologies to enhance real world performance metrics like longevity, power usage, and safety for their implantable brain device. Their current brain implant is getting close to mass production capable. That thing is a technological marvel integrating bluetooth communications, ARM processor to decode spikes in real time, power managements, battery and wireless power recharging all connected to 1024 probes, soon 16K thin wire probes. All hermetically sealed operating in a hostile environment (inside the human body).
And mass production they will need. The first questions came from neuroscientists who were salivating over the possibilities of this hardware for neuroscience research. While Neuralink is necessarily currently focused on real world injury mitigation applications (for revenue reasons), many neuroscientists want to figure out how the thinking parts of the brain work. How do we reason? How do we lay down memories? Anyways, research labs across academia will each want to buy whatever v1.0 kit Neuralink produces.
That 1.0 kit will include a surgery robot for implantation, the actual brain implant, and all the software systems that interpret the raw neuron spike data.
I can't emphasize enough just how many different advanced technologies Neuralink has already produced and worked on. In addition if they were an academic institution, they would have produce thousands of academic papers by now.
Finally, Elon. Elon started this as a way of producing better human/computer symbionts for the inevitable AI/human meshing. As he pointed out, we are already symbionts because our phones are already an extension of ourselves, and they provide access to the digital/information/communication world.
But all that is in the far future. His company, composed of real world engineers, is busy creating down to earth technologies that allow for brain reading and brain writing to solve current low hanging fruit problems. It is very analogous to SpaceX which was formed to create a civilization on Mars, but 20 years on is still "just" the world leader in orbital lift. Elon won't see his ultimate SpaceX dream in his lifetime, nor will he see all the things Neuralink will do, But along the way, Neuralink will have a profound impact on brain science and medical technology while being a profitable medical technology corporation.
More so than when Elon presents about his other companies, you could tell that Elon was barely hanging on when talking about this advanced medical/biological technology. When he spoke, it would be visionary, and when his engineers/medical experts answered the question (he had like 20 on stage, each giving a part of the presentation and all answering questions), it was very technical and to the point. This isn't surprising - Neuralink is the most far afield from his knowledge base company he has started.